The New Zealand Qualifications Authority is unlikely to reach its target of having NCEA exams completed online by 2020.
A computer glitch interrupted a pilot Level 1 digital English exam yesterday - which more than 3500 students were registered to take part in.
But a secondary school principal said technical difficulties were not the only hurdle to achieving the 2020 goal.
Some 46,000 students sat yesterday's Level 1 English exams. But for the 3600 students doing the digital pilot, things didn't all go to plan.
Just over two hours in, a computer glitch froze the screen for more than 20 minutes before it was cleared and students could get on with the exam.
NZQA said the issue was fixed within 10 minutes and the exam was extended to make up any time lost.
But Hayley Searancke, a Year 11 Kāpiti College student, said it was a major disruption.
"People were all affected in the classroom, they were all rustling about just really wondering how long it was going to be until we could get back into our work," Ms Searancke said.
Kapiti College Principal Tony Kane said the glitch was avoidable.
"This is an utterly known quantity, whoever was administering that part of it knows exactly how many students are going to be online at that time," Mr Kane said.
"In days where millions and millions of transactions happen everyday, surely 3500 kids on a digital exam is not a big ask."
Year 11 students at Auckland's Pakuranga College also had their exam interrupted by the glitch.
The school's principal, Mike Williams, said quite a few students were stressed by it.
NZQA is investigating digital assessment methods, with the aim of having NCEA examinations available online by 2020.
The aim to go digital then was optimistic, Mr Williams said.
"Invariably, we need to be in a better place but I don't know we will ever get to a place with digital devices where they never crash," Mr Williams said.
"It is implicit in the devices, there are hiccups, what we need to be able to avoid is when we have a mass online exam, the system is more robust."
Technical difficulties were not the biggest challenge standing in the way of the digital push, Mr Williams said.
"While there will always be these technical things to resolve and every step of the trials and pilots we learn more about the process, the biggest challenge for 2020 will be the equity issues across New Zealand of how do we provide an equitable learning environment for all students," he said.
"So giving all students access to devices - not just for an exam, but for their learning."
NZQA's Andrea Gray said it was unlikely all exams would be digital by 2020.
"We are seeing that the types of things that we would need to be able to see, like technology to take things like mathematics examinations successfully, may or may not be in wide use in schools so we're not going to rush, but we are able to implement most of the text based examinations next year and some of the foreign language ones the following year," Ms Gray said.
NCEA digital exams would remain optional for the foreseeable future, Ms Gray said